World number one Novak Djokovic said Lance Armstrong should "suffer for his lies" after finally admitting doping today, but insisted tennis was a clean sport with adequate testing.

Djokovic, speaking after Armstrong confessed to cheating his way to his seven Tour de France victories, said the American's behaviour reflected badly on all athletes and should be punished.

"I think it's a disgrace for the sport to have an athlete like this," Djokovic said at the Australian Open in Melbourne.

"He cheated the sport. He cheated many people around the world with his career, with his life story. I think they should take all his titles away because it's not fair towards any sportsman, any athlete.

"It's just not the way to be successful. So I think he should suffer for his lies all these years."

Djokovic also supported tennis's current anti-doping regime, which relies heavily on urine rather than blood tests, which are more accurate, despite fears it is not stringent enough.

"The results are showing that. In the last few years there maybe has been one or two cases, but those players were more or less outside of the top 100," said the Serb.

"We are keeping this sport clean. We are working towards it. There is awareness with the players and with the officials. As long as it is like that, we are in a good road."

Armstrong, who evaded cycling's testing authorities for years, finally admitted his clean image was "one big lie" in an interview aired on American television today. Tennis currently has a "whereabouts" system where players

must tell authorities where they will be for one hour every

day of the year. But Djokovic said he had not had a blood test

in the past "six, seven months".

"Yeah, I wasn't tested with blood for last six, seven months. It was more regularly in last two, three years ago. I don't know the reason why they stopped it," he said.

"As I said, I mean, as long as it's fair, it's clean, we're trying to protect the identity of this sport. I believe tennis players are one of the most cleanest athletes in the world and one of the most competitive sports.

"So as long as we keep it that way, I have no complaints about testing."